By no means the least important part of Flower’s work in connection with the museum of the College of Surgeons was the compilation and publication of the first two volumes of the _Catalogue of Osteological Specimens_ the first, dealing with man alone, issued in 1879, and the second, written with the aid of his assistant, Dr. J. G. Garson, and treating of the other members of the mammalian class, in 1884. The importance of these works consists in the fact of their being a very great deal more than mere catalogues of the contents of one particular museum. They are, on the contrary, systematic treatises, embodying the views of their chief author on such important subjects as zoological nomenclature and classification, and on the best method of arranging museums which include specimens of the dentition and osteology of both living and extinct animals. They accordingly deserve notice at some considerable length, not only on this account, but as forming a record of the great changes Flower introduced into the museum at this period under his charge. It appears that the first printed list of the contents of the museum was published in the year 1831. In a few years, however, it became evident that a work of a more ambitious nature was required; and in January 1842, the then Conservator, Professor Owen, presented a report to the Council, on the supreme advantage to be gained by combining in the proposed new Catalogue both the recent and the fossil osteological Catalogues. Acting on this, the Committee of Council resolved that such a Catalogue should be prepared and published, and the duty of doing this was thereupon confided to Mr. Owen. For some reason or other, this excellent and far-seeing resolution was not acted upon in its entirety; and although catalogues were in due course compiled by Owen and published, the specimens belonging to animals still extant were entered in volumes quite distinct from these devoted to fossil bones and teeth; while the two series of specimens were likewise kept apart in the museum itself. “Hence,” as Flower subsequently observed, “each series was incomplete, and required reference to the other for its perfect illustration and comprehension.” These defects were remedied during the administration of Flower, who not only arranged the extinct specimens in their proper position among those belonging to recent animals, but likewise followed the same admirable plan in drawing up the Catalogues. Later on, as we shall see in the sequel, he endeavoured to introduce the same scheme into the Natural History Museum, but was prevented by the force of circumstances from carrying his views into full effect, although a small step in the right direction was accomplished.